The DWV system has three functions: drains carry wastewater from fixtures to the sewer; waste lines carry solid waste; vent pipes connect the drain system to the atmosphere through the roof, equalizing air pressure so drains flow freely and preventing the siphoning of P-trap water seals. Every fixture requires a P-trap (the curved pipe under every sink that holds water to block sewer gases). Every P-trap must be vented within the code-specified trap-to-vent distance. Improperly vented drains produce slow drainage, gurgling sounds, and sewer gas odors. RainFire Builders designs DWV systems to meet Utah UPC requirements for trap-to-vent distances and vent pipe sizing.